Such transmissions for a motor vehicle are designed, inter alia, as so-termed dual clutch transmissions in which the input shafts of the two part-transmissions can each be connected by way of a respective, associated power-shifting element to a drive mechanism, for example an internal combustion engine or an electric motor, wherein the two power-shifting elements are combined in the form of a dual clutch. The gear steps that can be obtained by means of such a transmission are then distributed alternately between the two part-transmissions, so that, for example, one part-transmission produces the even-numbered gears and the corresponding other part-transmission produces the odd-numbered gears. It is also known to obtain the individual gear steps by means of one or more gear stages or planes, each having different gear ratios. By means of corresponding shifting elements these can be connected into the force or torque flow between the drive input and the drive output, so that a corresponding, desired gear ratio between the drive input and the drive output of the transmission is obtained in each case.
By virtue of the alternating distribution of the gears between the two part-transmissions it is possible, while driving in a gear associated with one of the part-transmissions, to already preselect a next gear in the respective other part-transmission by appropriate actuation of the shifting mechanisms, so that an eventual change to the next gear is effected by opening the power-shifting element of the one part-transmission and shortly afterward closing the power-shifting element of the other part-transmission. In this way the gears or gear steps of the transmission can be shifted under load, which improves the acceleration ability of the motor vehicle by virtue of a gear change effected essentially without interruption of the traction force and enables more comfortable shifting processes for a driver of the vehicle.
Such dual clutch transmissions can also be designed with an intermediate transmission additional to the drive input and output, so enabling a more compact structure in the axial direction.
DE 10 2006 054 281 A1 has made known a transmission of this type for a motor vehicle, in the form of a dual clutch transmission. The dual clutch transmission has two part-transmissions, each with an input shaft. By connecting the respective input shafts in each case by means of a power-shifting element the two part-transmissions can each be connected in alternation into a force or torque flow from a drive input to a drive output, the input shaft of the first part-transmission being made as a central transmission shaft whereas the input shaft of the second part-transmission is made as a hollow transmission shaft. In addition an output shaft is provided, which forms the drive output of both part-transmissions so that a rotary movement of the drive input can be transmitted to the drive output via a plurality of gear ratio steps, and the force and torque flow passes via an intermediate transmission. In this case at least two gear planes are engaged in the force and torque flow by the actuation of associated shifting elements, so that a number of gear ratio steps can be obtained by combining the actuation of the shifting elements and the force and torque flow by way of appropriate gear planes. Likewise, by actuating appropriate shifting elements the rotary movement of the drive input can be transmitted to an output shaft of the drive output without geared conversion.